The present invention relates to polyurethane foam moldings having excellent abrasion resistance useful for automotive material for steering wheels, headrests and armrests, material for furniture and the like.
Integral skin polyurethane foams having fine pore skin are well-known to the public and are widely utilized as automotive material for steering wheels, headrests and armrests, and material for furniture and the like in various fields. The formation of the skin layer in the integral skin foams is based on the function of a blowing agent such as chlorofluorocarbon ("CFC") in the exothermic reaction of a polyisocyanate with a polyol. The use of a physical blowing agent such as CFC provides to the foams excellent skin properties which are required for the stated products. On the contrary, the use of a chemical blowing agent such as water does not usually provide excellent skin properties to the foams.
Some approaches to provide excellent skin properties to polyurethane foam moldings have included, for example, those described in Japanese Kokai Patent No. H03-24108, in which a specific catalyst mixture comprising a urethane catalyst and a carbodiimide catalyst is employed to provide low core density in the presence of a non-reactive physical blowing agent, and Japanese Kokai Patent No. H03-33120, in which a specific catalyst mixture is employed in the presence of water as the primary blowing agent. The technology disclosed in the latter patent may be especially useful as an alternative technology to a CFC based blowing agent under the Freon Regulation.
Since several years ago, it has been pointed out that CFC destroys the ozone layer of the Earth, and consequently, the use of CFC is globally expected to be restricted or abolished in various industrial fields in present and future. In such situation, some approaches to employ water as the primary blowing agent have been tried. However, in such prior art, there is a technical problem that polyurethane foams prepared employing water as a sole blowing agent are not better in skin properties and abrasion resistance than foams prepared employing CFC as a blowing agent.